In an elastic collision, no energy is lost. This means that the collective energy of the objects that collide, before the collision and after, is the same. In other collisions, energy is lost due to things like friction, deformation of the objects, sound, etc.

An explosion collision is a perfectly inelastic collision run in reverse. A perfectly inelastic collision represents the maximum amount of energy that can be lost (or gained, in this case) during the collision.

Elastic: No energy is lost by the colliding objects. Maximum boingy.

Inelastic: Energy is lost by the colliding objects.

Perfectly inelastic: The maximum amount of energy is lost by the colliding objects. Sticky.